Remission by adulthood of childhood ADHD is estimated in approximately half of all cases; however, this conclusion is typically based on single endpoints, and little evidence exists regarding the longitudinal patterns of ADHD expression. The objective of this study was to investigate longitudinal patterns of remission from ADHD in the Multimodal Treatment Study of ADHD (MTA) (MTA Cooperative Group, 1999) to assess the extent to which children with ADHD experience recovery and variable patterns of remission by adulthood.
This present study analysed 558 children included in the MTA, all of whom underwent eight assessments over follow-ups ranging from 2 years (mean age, 10.44 years) to 16 years (mean age, 25.12 years) after baseline. Authors identified participants with fully remitted, partially remitted or persistent ADHD at each time point, based upon data obtained from the MTA assessments. These data included parent-, teacher- and self-reports of ADHD symptoms and impairment, treatment utilisation, and substance-use and mental disorders. The authors identified longitudinal patterns of remission recurrence and recovery from ADHD, which considered context and timing.
In this study, the mean (standard deviation [SD]) age of the MTA sample was 10.44 (0.87) years at 2 years and 25.12 (1.07) years at the 16-year follow-up. The percentage of fully remitted cases ranged from 1.4% (at the 2-year assessment) to 18.5% (at the 10-year assessment), whilst the percentage of partially remitted cases ranged from 37.2% (at the 10-year assessment) to 51.4% (at the 2-year assessment). The percentage of persistent cases, which was defined as meeting Diagnostic and Statistical Manual of Mental Disorders – 5th Edition criteria* for ADHD, ranged from 39.7% (at the 14- and 16-year assessments) to 55.9% (at the 6-year assessment).
Overall, 31.4% (n=175) of the sample met criteria for full remission for at least one of the timepoints. Amongst the 175 cases of full remission, 59.4% (n=104) demonstrated full (29.1%) or partial (30.3%) recurrence of ADHD after the initial episode of full remission. In contrast, recovery from ADHD by the final MTA assessment was identified in 9.1% of the sample, with a mean (SD) age of 25.12 (1.07) years. In this group, the median duration of the recovery period was 4 years, and onset of recovery came in adulthood for 76.5% (n=39), in adolescence for 21.5% (n=11) and in childhood for 2.0% (n=1) of participants.
At all timepoints, 10.8% (n=60) of the sample were in the persistent category, 15.6% (n=87) experienced partial remission that was maintained throughout the study until the endpoint, and the majority (63.8%; n=356) demonstrated a pattern of fluctuating ADHD. Four cases were not included in the longitudinal analysis due to insufficient information availability. In addition, supplemental analyses were conducted which illustrated longitudinal classifications by collapsing full and partial remission statuses into one ‘remission’ category. When the data were categorised in this way, 48.5% of the sample demonstrated a pattern of fluctuating ADHD by study endpoint.
The authors identified several limitations associated with this study. In particular, they noted that the greatest limitation was the discontinuation of the MTA follow-up when participants were approximately 25 years of age, which prevented determining whether longitudinal trends continued into middle and older adulthood, or whether the recovery pattern reflected permanent remission. The generalisability of the results to other ADHD subtypes or presentations was another limitation of the study because the MTA sample only recruited participants with combined-type ADHD. It should be noted that the definitions of full and partial remission of ADHD applied in this study may have influenced the results, and alternative definitions may have led to different estimates. Further to this, requiring an informant to verify self-reports of remitted ADHD may have produced some false-negative full remission classifications. Additionally, sensitivity analyses suggested that missing data and source switching may have affected the fluctuating pattern of ADHD in participants. Another limitation was that during childhood and adolescence, impairment ratings were available only from parents, and not from teachers or self-ratings, which may have led to fewer reports of adolescents meeting impairment criteria. Similarly, in post-secondary academia, teacher ratings were no longer available, which may have led to symptoms going undetected at this stage. The authors identified cut-points, which were used for symptoms and impairment thresholds, as potential causes of statistical error. Finally, the authors indicated that treatment effects could not be entirely accounted for in this study.
The authors concluded that this study provided a more informed perspective on ADHD, its impairment, and its tendency to fluctuate over time in symptoms and impairment, which may be related to environmental or health-related factors. They suggested that healthcare providers should expect recurrence of clinically elevated ADHD symptoms and impairments in most individuals who experience remission, and recommended continued periodic screening for recurrent symptoms and impairments after successful treatment. The authors highlighted the need for the assessment of factors that may influence symptom fluctuations and suggested that clinicians communicate to families the high chance that children and adolescents will experience intermittent relief from their ADHD symptoms over time.
Read more about the patterns of remission from ADHD here
*The American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders – 5th Edition (DSM-5TM) is a classification of mental disorders with associated criteria designed to facilitate more reliable diagnoses of these disorders (American Psychiatric Association, 2013)
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American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Washington, DC: American Psychiatric Association, 2013.
Sibley MH, Arnold LE, Swanson JM, et al. Variable patterns of remission from ADHD in the Multimodal Treatment Study of ADHD. Am J Psychiatry 2021; Epub ahead of print.
The MTA Cooperative Group. A 14-month randomized clinical trial of treatment strategies for attention-deficit/hyperactivity disorder. Arch Gen Psychiatry 1999; 56: 1073-1086.